Wireless communication between Arduinos is getting cheaper and easier as the days pass. Flutter makes integrating wireless connection into your projects cheaper and easier than ever.
The USP of Flutter (apart from the low cost) is the range that it can achieve. Half a mile, or 1km for you metric heads, is a considerable distance when compared to ordinary Wi-Fi's maximum distance of about 300 feet (~100m). Couple this with Flutter's "Mesh Networking" (sending data through multiple devices) and you get some real long range communication possibilities.
There are 2 versions in development: Flutter Basic ($20) and Flutter Pro ($30). The Pro version adds battery charging, a screw mount antenna, and more memory to store your code (the Flutter Basic is still in development however).
So you are not left hanging with just a board, Flutter also has 4 shields available to get you up and running. Each board comes with a breakout board included, so you can create a permanent project, yet still be able to remove the Flutter if you need it elsewhere. There is also an RC shield for remote control cars, a network shield for you to connect to the web via Ethernet or Wi-Fi, and a Bluetooth shield so you can easily connect to your phone.
The Flutter developers have also addressed the issue of security with their own cryptographic system built into both the hardware and software.
To make Flutter as secure as possible, we’re building in special cryptographic hardware and integrating cryptography into every layer of the software, giving the user ultimate control over who can and cannot communicate with their devices.
In addition to software for handling encryption and decryption of data, flutter uses the cryptographic chip as the hardware element of the security system. Built specifically for use in high security applications, the Atmel ATSHA204 is based around secure storage for protecting your encryption keys.
As with all things based on Arduino, and most Kickstarter projects, the entire project will be open source, allowing you to delve and hack as deep as you want. You can donate to help them reach their $80,000 target, and a $30 pledge will get US backers a Flutter Basic delivered to their door (albeit next April).
EDIT:
The campain has ended, and shipping will start any day.